There is always a need for protective helmets which may reduce possible personal injuries in case of accidents. For this purpose, several types of helmets have been developed, among which are helmets with helmet liners. However, there is also a need for a helmet which provides as good protection as possible. By making helmet liners with knobs being deformable, a reduction of the forces reaching the head of a user in case of impact, e.g., in connection with accidents. There exists a need a helmet with a helmet liner which provides as good a protection as possible.
For this purpose, helmets having helmet liners both with cuttings and energy-absorbing knobs have been developed. These helmet liners have previously not been optimized with a view to the distribution, orientation, location and form of the knobs. For this reason, there is also a need for a helmet liner which may help mending this problem.
For production of such helmet liners, several types of manufacturing processes have been attempted, e.g., injection moulding in a mould and vacuum moulding on a hemispherical rigid dome having protrusions distributed on the dome. The tools which are utilized for injection moulding are as a rule more expensive that the tools which are utilized for vacuum moulding. A problem with vacuum moulding on a rigid dome-shaped mould is that it is the moulding process which becomes vital for distribution, orientation and arrangement of the knobs. A helmet liner being moulded with undercut may be damaged when it is removed from the mould, at any rate, the percentage of rejects would be high. Pressforming of the material in on a flat mould have also been attempted, so that the moulded material receives the shape of half an unfolded globe to be folded and fastened to the desired shape. This process is a time-consuming, complicated and expensive process which does not necessarily provides a helmet liner of sufficient quality. In order to be able to manufacture a helmet liner having the desired orientation, arrangement and distribution of the knobs for an optimal protection of the head of the user, there is a need for a more reasonable process for manufacturing helmet liners with desired properties. The present invention solves these challenges.